Generally, cult classics are the ones that failed the most. Blade Runner, Abyss, Boondock Saints, etc. They were commercial failures, but gained new life when they were re-released as Director's Cuts or were made available for rental/purchase. The problem with something like Valerian, is that it is a modern film, so it is not something that will be talked about inbetween classes in college, during lunch in primary school, or passed from friend to friend. There is just too much content available at any given point that people will just watch something "better" without really giving it a chance.